What your EVO needs for a fuel system, facts.
Jan 14, 2007, 07:23 AM
#31
Alright, I got called out on my math by l2r99gst and he was correct. I accidently figured these HP levels at 80% like you would a duty cycle on an injector. So, I made a mistake
The original post #1, will be fixed immediately to reflect the correct information.
Sorry for the mistake, I used the wrong damn formula.
The original post #1, will be fixed immediately to reflect the correct information.
Sorry for the mistake, I used the wrong damn formula.
Jan 14, 2007, 07:46 AM
#32
Dave,
Would you share the formula you're using for calculating the flywheel HP that the pump will support?
All formulas make some assumptions that generalize among motors. My calculations for flywheel HP produce lower supported HP numbers than your formula apparently does, but as long as everyone understands that these don't relate directly to dyno numbers, we're all on the same page. Drivetrain losses would reduce the flywheel numbers by 17-25%, depending on the 4WD system, so 600HP flywheel might translate to 480HP measured on the dyno...
What was useful to me in reviewing your numbers was (1) that there does not seem to be much difference in availalbe fuel volume flow comparing the stock Walbro and the HO Walbro,unless you're running more than 40 pounds of boost and (2) that even using your HO modified Walbro, your direct dyno experience was that you documented fuel starvation effects at around 500+ HP dyno HP at the wheels. You adjusted the fuel curves and used bigger injectors to work around the problem before the dual pump solution, right?
Would you share the formula you're using for calculating the flywheel HP that the pump will support?
All formulas make some assumptions that generalize among motors. My calculations for flywheel HP produce lower supported HP numbers than your formula apparently does, but as long as everyone understands that these don't relate directly to dyno numbers, we're all on the same page. Drivetrain losses would reduce the flywheel numbers by 17-25%, depending on the 4WD system, so 600HP flywheel might translate to 480HP measured on the dyno...
What was useful to me in reviewing your numbers was (1) that there does not seem to be much difference in availalbe fuel volume flow comparing the stock Walbro and the HO Walbro,unless you're running more than 40 pounds of boost and (2) that even using your HO modified Walbro, your direct dyno experience was that you documented fuel starvation effects at around 500+ HP dyno HP at the wheels. You adjusted the fuel curves and used bigger injectors to work around the problem before the dual pump solution, right?
Jan 14, 2007, 08:09 AM
#33
Alright, I got called out on my math by l2r99gst and he was correct. I accidently figured these HP levels at 80% like you would a duty cycle on an injector. So, I made a mistake
The original post #1, will be fixed immediately to reflect the correct information.
Sorry for the mistake, I used the wrong damn formula.
The original post #1, will be fixed immediately to reflect the correct information.
Sorry for the mistake, I used the wrong damn formula.
Thanks for the great product and all of the testing that you put into this.
Eric
Jan 14, 2007, 09:07 PM
#43
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^^ Yup, that is the question. I did a little searching, the model number is 195130-1020, I guess RRE sells them. Denso has them listed at $190.00 MSRP on their site, so not bad at all. Suprisingly E-bay had them for $235.00.
I'm hoping either the Buschur unit or Full Blown unit can be modified to fit a pair of them, or single depending on needs. CO_VR4 was sending Full Blown a 1020 to measure and whatnot.. (I hope..)
I'm hoping either the Buschur unit or Full Blown unit can be modified to fit a pair of them, or single depending on needs. CO_VR4 was sending Full Blown a 1020 to measure and whatnot.. (I hope..)
Last edited by Frenchy4g63; Jan 14, 2007 at 09:26 PM.
Jan 14, 2007, 10:01 PM
#44
First let's talk about the fuel pumps. Most every EVO shop that sells a Walbro pump for an EVO sells the GSS342 pump.
Here are the specs on that pump at boost levels that are important. This is flow testing the pump at 13.2 volts.
0 psi the pump flows 515 lb/hr
40 psi the pump flows 410 lb/hr
60 psi the pump flows 360 lb/hr
70 psi the pump flows 332 lb/hr
80 psi the pump flows 285 lb/hr
100 psi the pump flows 160 lb/hr
The reason these levels are important is it shows the fuel pumps are rated at 255 lt/hr at 0 psi. Nobody cares about that as the car doesn't run at 0 psi of fuel pressure.
Here are the specs on that pump at boost levels that are important. This is flow testing the pump at 13.2 volts.
0 psi the pump flows 515 lb/hr
40 psi the pump flows 410 lb/hr
60 psi the pump flows 360 lb/hr
70 psi the pump flows 332 lb/hr
80 psi the pump flows 285 lb/hr
100 psi the pump flows 160 lb/hr
The reason these levels are important is it shows the fuel pumps are rated at 255 lt/hr at 0 psi. Nobody cares about that as the car doesn't run at 0 psi of fuel pressure.
From Walbro's own testing they show the 255 rating (255lt/hr=67gal/hr) at 40psi and 13.5V not 0psi. This from http://www.autoperformanceengineering.com/
Look in the left column and click technical then check out the 13.5V table. GSS342 is the "high" pressure 255 listed. Also shows a pic of the GSS340 (left), GSS342 (middle), and GSS341 (right).
Last edited by Drifto; Jan 14, 2007 at 10:06 PM.
